We get more feature requests than we can deal with, so if you're making a suggestion you should describe a really good use case that shows how it's important and why it should be prioritised over other things.

Ooh, that's a really good point. It might murder performance, but if handled delicately, having the ability to change particle sprites on-the-fly is a nice workaround to the limits of the particle object for those people who want them.

Of course, the question is: would this affect all particles currently in the system, or only those as they're generated (to make a random particle generator, for example).